Perception

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Chapter 4

• Perception

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Percept

• . . . a mental representation of a stimulus that
  is perceived

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James Gibson (1966)

• Distal Object an object in the external world

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James Gibson (1966)

• Distal Object an object in the external world
• Informational Medium the medium through which
  we perceive the distal object

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James Gibson (1966)

• Distal Object an object in the external world
• Informational Medium the medium through which
  we perceive the distal object
• Proximal Stimulation stimulation of our sense
  organ perceiving the distal object

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James Gibson (1966, 1979)

• Distal Object an object in the external world
• Informational Medium the medium through which
  we perceive the distal object
• Proximal Stimulation stimulation of our sense
  organ perceiving the distal object
• Perceptual Object perception of the distal
  object into a meaningful whole

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Perceptual Constancies

• Size Constancy objects maintain their size no
  matter how close or far they are

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Perceptual Constancies

• Size Constancy objects maintain their size no
  matter how close or far they are
• Shape Constancy objects maintain their shapes
  no matter what their orientation

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Depth Perception

• Monocular Depth Cues factors such as grain,
  size, and parallax

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Depth Perception

• Monocular Depth Cues factors such as grain,
  size, and parallax
• Binocular Depth Cues factors such as eye
  convergence and disparity

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Gestalt Approaches to Form Perception

• Figure-Ground

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Gestalt Approaches to Form Perception

• Figure-Ground
• Proximity

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Gestalt Approaches to Form Perception

• Figure-Ground
• Proximity
• Similarity

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Gestalt Approaches to Form Perception

• Figure-Ground
• Proximity
• Similarity
• Continuity

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Gestalt Approaches to Form Perception

• Figure-Ground
• Proximity
• Similarity
• Continuity
• Closure

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Gestalt Approaches to Form Perception

• Figure-Ground
• Proximity
• Similarity
• Continuity
• Closure
• Symmetry

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Theoretical Approaches to Perception

• Bottom-Up Theories

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Theoretical Approaches to Perception

• Bottom-Up Theories
• Top-Down Approaches Constructive Perception

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Theoretical Approaches to Perception

• Bottom-Up Theories
• Top-Down Approaches Constructive Perception
• David Marrs (1982) Computational Theory of
  Perception

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Bottom-Up Theories

• Direct Perception our sensory receptors are
  sufficient for perception

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Bottom-Up Theories

• Direct Perception our sensory receptors are
  sufficient for perception
• Template Theories templates of objects are
  stored in our minds and used to perceive new
  objects

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Bottom-Up Theories

• Direct Perception our sensory receptors are
  sufficient for perception
• Template Theories templates of objects are
  stored in our minds and used to perceive new
  objects
• Prototype Theories abstract central tendencies
  of categories form the categorical prototype and
  are used to categorize new objects

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Bottom-Up Theories, cont.

• Feature Theories rather than whole objects or
  prototypes, prominent features of objects are
  used to categorize new objects

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Bottom-Up Theories, cont.

• Feature Theories rather than whole objects or
  prototypes, prominent features of objects are
  used to categorize new objects
• Structural-Description Theory (Recognition-by-Comp
  onents or RBC Theory) objects are made up of
  basic geometric ions (geons), and the geons we
  have stored are used to recognize objects

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Top-Down Approaches Constructive Perception

• The use of higher-order thought processes to
  assist in the perception of objects. These
  higher-order cognitions include our understanding
  of context and previous experiences.

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David Marrs (1982) Computational Theory of
Perception

• In visual perception, we use three kinds of
  features edges, contours, and regions of
  similarity. We first construct a 2-dimensional
  representation of 3-dimensional objects, then we
  elaborate upon this construction to create a 2
  ½-dimensional representation, adding depth cues
  and surface orientations. Finally, we construct a
  richer 3-dimensional representation of the object.

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Deficits in Perception

• Agnosia, which means without knowledge or lack
  of knowledge in Greek. This is a condition where
  our sensory organs cannot determine what objects
  are.